The present invention relates to a mechanical return blocking device and further a device where such a mechanical return blocking device is incorporated.
Return blocking devices may be used for a multitude of purposes.
An example of a return blocking device for maintaining a window or door in an open position is known from U.S. Pat. No. 2,129,412. In particular in the second embodiment of this document, a return blocking device is described where a ratchet is arranged inside a housing. Through a slit in the housing, a second movable member is inserted. The movable member comprises an engagement section which is adapted for engagement with the ratchet. As the second member moves in a first direction, counter movement will be hindered by the triangular shape of the ratchet. When the second member comes to the end of the ratchet, it will, due to the influence of a spring, be pushed downwards, whereby travel is allowed in the opposite direction under the ratchet. Due to the further provision of a second spring member, the second member will be guided upwards towards the beginning of the ratchet such that forward movement may be possible again. This construction comprises a number of drawbacks, for example the entire construction is placed in a housing, whereby debris or other foreign objects stuck inside the housing eventually will hamper the proper working of the device. For example, if foreign matter has become wedged between the second spring device and the bottom of the device, it will not be possible to push the engagement section back up on the second track. Furthermore, foreign matter stuck under the ratchet, i.e. between the second track and the first track, will likewise hinder the proper functioning of the device. Also, as it is evident from further embodiments of the present invention, this device does not allow for the movable member to return to the first position halfway through the ratchet, but needs to continue all the way to the end in order to fall down to the first track provided underneath the ratchet in order to travel backwards to the original beginning position. Furthermore, the proper workings of the device is wholly dependent on the ability of the second spring member to force the engagement section back up at the level of the ratchet means, otherwise the device will be completely useless.
From the prior art document FR 2169664 is known a device for use in order to maintain a window in a more or less open position in relation to a frame. The device comprises two co-axially arranged and mutually displaceable arm parts as well as a locking member which is pivotally and biasly arranged in the outer member of the two co-axially arranged members such that a notch on the locking member may engage a centrally located displaceable member. The locking notch will travel on inclined surfaces and will be guided from one track to the opposite track on the inclined surfaces in relation to different retaining possibilities arranged on the interior member along the locking members' travel. In order to allow movement, the pivotal locking member must be pivoted manually onto one or the other track in order to decide whether the window shall be more or less open.
In a further embodiment in this prior art invention, the locking member is provided with a spring biasing means such that accidental relative movement of the two co-axially arranged parts does not cause the window to move in relation to the frame without actively and forcefully bringing the locking member out of engagement with the co-axially internal member.
It is, therefore, an object of the present invention to provide a mechanical return blocking device which alleviates these disadvantages, and at the same time provides a number of further advantages, which provides for a wide range of applications, wherein the device according to U.S. Pat. No. 2,129,412 would not be considered suitable.
In a number of applications a certain task is performed or carried out by manually depressing a button or lever, which in turn causes one or more events to happen.
In a number of these applications it is desirable to assure that either a stroke of the button or lever has been performed or at least that the stroke of the button or lever was sufficient in order to activate the event in question.
Below as an example of devices where this situation is important will be discussed an example relating to an asthma inhalation device.
These types of asthma inhalation devices function in a way whereby the user/patient when needing to inhale the medication places the asthma inhalation device with a mouthpiece in the patient's mouth and thereafter activates a button. By depressing the button a canister inside the device is activated such that a medication dose stored in the valve system in the canister is dispensed through the mouthpiece to the patient.
Often these types of devices comprise a dose counter such that the patient will be able to keep track of how many doses are left in the device such that a new device or canister can be provided in due time. It is therefore important that when the patient dispenses a dose, only one dose is dispensed and at the same time only one dose is counted.
Due to inherent tolerances in production in order to keep production costs of these types of devices as low as possible, and furthermore as a consequence of the play arising from a number of mutually cooperating parts, it is sometimes possible to activate the bottom either from the non-depressed state or from the semi-depressed state, whereby the dose counter may be activated without an actual dose being dispensed or a dose may be dispensed without activating the dose counter.
For this type of device as for many other types of devices it is undesirable that depression of a button/lever, which is intended to effect a function, i.e. initiate an event, where said function may have more than one result, i.e. the example mentioned above, the activation of the button shall result in the dispensation of a dose and at the same time counting/registration of said dose. It is paramount that both these events happening by depressing the bottom are reliable registered and carried out without the possibility of unintended or intended tampering with the device.